Reproductive Cloning
Overview and Method Reproductive cloning is the process of producing genetically identical multicellular organisms by the use of somatic cell nuclear transfer (SCNT). Somatic cell nuclear transfer involves removing the nucleus from a somatic cell of an organism and inserting it into an egg that has had its nucleus removed. Certain stimulation, such as chemicals or electrical current, can cause the cell to divide and produce a clonal embryo. The embryo can be implanted into the uterus of a gestational surrogate and carried to term. The birth of the newborn results in a baby genetically identical to the original organism. However due to the mitochondrial DNA not being copied and transferred, those produced from somatic cell nuclear transfer are not completely identical to the original. History of Reproductive Cloning The first nuclear transfer was performed in 1928 by Hans Spemann. In his experiment, he transferred the nucleus of a salamander embryo cell to a cell of which the nucleus had been removed. In 1952, Robert Briggs and Thomas J. King followed up this experiment by using embryonic donor cell nuclei from amphibia. During this experiment, Briggs and King successfully cloned thirty- five complete embryos and twenty- seven tadpoles. Ten years later in 1962, Oxford University scientist John Gurdon discovered that when a cell nuclei differentiates, no genetic material is lost, suggesting that differentiation of cell nuclei can result in cloning. Gurdon's work attracted the attention of many scientists, however, many questioned the validity of his results due to many flaws found in his procedure. Experimentation and research from the 1970s through the 1990s kept the idea of cloning mammals a close reality. Then, in 1996, Ian Wilmunt and Keith Campbell successfully conceived the first mammal clone from an adult nucleus. In 1997, Dolly the sheep was born, which initiated a world-wide discussion of the possible cloning of other mammals and humans. Genetics and Genomics Uses There are many possibilities for reproductive cloning to be beneficial in the world of genetics and genomics. Today, many mammals have been cloned, such as horses and mice, however, there is discussion about cloning humans. Although it isn't scientifically possible yet, if successfully done, it has been discussed it can be used for many purposes. The main purpose for cloning humans would be to produce a genetically identical donor for those that cannot obtain tissue or organs in any other way. It is suggested that human cloning could also be a novel form of human reproduction. Couples that cannot receive children through other fertility methods, lesbian couples, and single women can use human cloning to produce a genetically identical baby without having to use a sperm donor. Controversy Reproductive cloning is a very controversial process. Many people believe that life begins at conception and cloning is unnatural. Others believe that there are more risks than benefits of cloning copies of living organisms. About 98% of human cloning has resulted in miscarriages or still births and there are high chances that human clones will have subtle abnormalities due to the genetic mechanisms that are not yet understood. Also, cloned organisms have a significantly shorter life expectancy, which causes a great deal of controversy. Although reproductive cloning is a controversial subject, there are only laws against it in some states. Many states are open to experimentation with both animal and human cloning. References 1. Reproductive Cloning, BioCentre. 2. What is Reproductive Cloning? wiseGEEK. 3. About Reproductive Cloning. Center for Genetics and Society. 4. How Are Cloned Animals Made? LiveScience.